My long-term career goals are to become an independent investigator studying the role of cell death in diseases of the Gl tract. My previous research experience in cell and molecular biology related to cell death included my doctoral dissertation on the role of mitochondrial mutations in age-related disease. I have identified a highly successful mentor in the area of cell death in hepatobiliary diseases, including cancer. The lab is in the conducive environment of the Center for Basic Research in Digestive Diseases, at Mayo Clinic, Rochester. This proposal outlines a testable hypothesis to define the role of microRNAs as regulators of apoptosis in cholangiocarcinoma, a malignant neoplasm that occurs in the presence of chronic inflammation of bile ducts. The current proposal will allow the candidate to change research directions by providing advanced training in hepatobiliary disease and cancer biology as it relates to cell death. Short-term career goals include advanced training in cancer biology and Gl-related translational research. These immediate goals will be achieved by the career development plan, including research, communication skills, and mentoring training. The research plan stems from our previous observations that the antiapoptotic protein Mcl-1 is over-expressed in human cholangiocarcinoma and is a key regulator of cell death. One potential mechanism of Mcl-1 regulation is through microRNAs, short RNAs that act as sequence-specific silencers of protein expression. Our preliminary data shows that Mcl-1 expression is a predicted target of mir-29b, and antagonism of mir-29 increases Mcl-1 protein expression. Further, Mcl-1 is over-expressed in cholangio- carcinoma cells while mir-29b expression is decreased. Finally, blocking mir-29 protects cholangiocytes from cell death. These extensive and original observations support the OVERALL HYPOTHESIS of this grant that dysregulated expression of mir-29b results in over expression of Mcl-1, rendering this cancer apoptosis resistant. To address this hypothesis, we have established advanced cell culture models and molecular techniques to detect and alter expression of microRNAs. This project is relevant to public health as it addresses how bile duct cancers resist cell death, and as such resist chemotherapy. In addition, by testing a new pathway governing cancer cell death, we may define a novel set of targets to improve treatment of this devastating disease.